Plus it's virtually impossible to visually scan log messages as they go by when they're 10 lines long per entry vs 1 or 2 lines long.
I agree with the simplicity approach I like it too. However, I think sometimes we do not have a choice especially in distributed sytems or "micro"services environement. I think with great "complexity" comes great responsibility.
For simple enough logs (like the nginx/apache example shown) having so simple format enables a quick and dirty search and information extraction with common unix command line tools (like grep, cut, sort, uniq, tail and sometimes rev or awk). It is not an approach that works for all logs and all situations, but sometimes is enough. And simplicity is a good thing to have.